1. Field of the Invention
This invention relates in general to a method of manufacturing thin film electromagnetic flying head assemblies, and more particularly, to a method of providing adhesion support during the photolithography process used for defining the air bearing surface geometry of sliders while decreasing air bearing rail and/or pad surface areas and maximizing profit and productivity.
2. Description of Related Art
Disk drive systems are widely used to store data and software for computer systems. A disk drive system generally includes a disk storage media mounted on a spindle such that the disk can rotate thereby permitting an electromagnetic head mounted on a movable arm to read and write information thereon. Data read/write operations are performed by positioning the head to a selected radial position on the surface of the rotating disk. There the head reads or writes data in the form of magnetized regions on the platter coating.
The electromagnetic head for a disk drive system is usually mounted in a carrier called a "slider." The slider serves to support the head and any electrical connections between the head and the rest of the disk drive system. The slider maintains a uniform distance from the surface of the rotating disk to prevent the head from undesirably contacting the disk. This is accomplished by incorporating aerodynamic features into the slider that causes the slider to glide above the disk surface over the moving air.
Computer users constantly hunger for more and more data-storage capacity. Thus, disk drive makers are forever trying to increase the storage capacity of their products. They are also constantly trying to minimize the actual, physical size of those drives. The accomplishment of these goals requires both shrinking the spacing of the cylinders so that more data can fit on a disk and squeezing bits more closely together on the tracks. Thus, disk drive manufacturers must develop heads that are narrower or that record narrower tracks.
Another very important parameter is the height at which the head flies above the surface of the platter. The magnetic field pattern around the gap in the head spreads and weakens very rapidly with distance away from the gap. Because the relevant distance is from the gap to the magnetizable platter coating, the design must include both the air gap (the actual height at which the head flies above the upper surface of the platter) and the thickness of any protective or lubricating overcoating that may have been applied to the platter. Thus, disk drive manufacturers must develop ways of minimizing the height at which the head flies above the disk surface.
One example of the fabrication of a thin film head/slider combination is U.S. Pat. No. 5,095,613, issued Mar. 17, 1992, to Hussinger et al., entitled "THIN FILM HEAD SLIDER FABRICATION PROCESS", incorporated herein by reference, which discloses fabricating a head assembly from a bar on which electromagnetic devices are provided as a single row and with like orientation. The bar is integral along a second surface with an adjacent substrate portion. The bar is anchored to a fixture. Head assemblies are formed along the bar where immediately thereafter the individual head assemblies are separated. Then, the surface of the electromagnetic devices are exposed and processed. Finally, the exposed surface is lapped and ground until a desired throat height of the poles and a desired contour of the bar are obtained.
Another method of fabricating thin film head/slider combination is U.S. Pat. No. 4,333,229, issued Jun. 8, 1982, to Michael L. Ellenberger, entitled "METHOD OF MANUFACTURING THIN FILM MAGNETIC HEAD/SLIDER COMBINATION", incorporated herein by reference, which discloses depositing transducers onto a substrate member adjacent a finished and lapped surface in a manner such that no further lapping of the slider rail adjacent the transducer is required. The method includes forming recesses on the substrate member to define slider rails and then forming air bearing surfaces on each rail.
While each of the above patents discloses methods for forming the air bearing surfaces on the slider, the air bearing surface areas are still too large to meet the current nominal head/disk spacing requirements. The air bearing surface area is proportional to slider flying height. In order to reduce the head/disk spacing, slider air bearing surface geometry features must therefore become smaller and more intricate. As the nominal head/disk spacing requirements shrink for each new product, air bearing rail and/or pad surface areas must also become smaller. Furthermore, zone bit recording technology makes it desirable for the head/disk spacing to remain constant across all disk radii.
Air bearing surface geometries which can achieve the required insensitivity to the varying velocity and skew ranges are necessarily complex. And as the overall slider dimensions are reduced from nano to pico sizes and smaller to facilitate cost and productivity gains, the slider air bearing surface (ABS) features must also be proportionately scaled.
The definition of these smaller and complicated ABS features presents a challenge to the photolithography process. The depth requirements of the slider etching requires the use of a thick photoresist layer. But the small intricate ABS features provide an extremely small footprint for resist adhesion to the slider row surface. As a result, the exposed photoresist is extremely susceptible to chipping and flaking off during later processing and handling. If the resist has broken off the slider surface, the etching process will not define the ABS properly resulting in missing features and damaged rail surfaces.
Since sliders with these etch defects represent a significant risk to file reliability, it is necessary to implement costly inspection procedures to prevent shipment of these parts. Furthermore, materials costs are increased and manufacturing capacity is stressed due to yield losses. Therefore, it is necessary to implement a scheme to enhance photoresist adhesion and resistance to damage.
Therefore, it can be seen that there is a need for a method for etching small air bearing surfaces geometries for disk drive slider assemblies.
It can also be seen that there is a need for a method for aiding adhesion of masks to define small features on a transducer carrying slider.
It can also be seen that there is a need for a disk drive system where the head assembly has a transducer carrying slider fabricated with nano, pico or smaller size air bearing surfaces.
Finally, it can also be seen that there is a need for a slider fabrication method that prevents the chipping and flaking off of the photoresist during processing and handling.